Slim line battery pack

ABSTRACT

A battery pack is configured to reduce weight, enhance battery identification, ensure proper placement of a lid retaining the battery, and facilitate battery pack removal. The battery pack has one or more cells that lack an outer coverage except for a polymer sheathing. The battery pack includes a mating notch on a terminal plate and may include a fingernail notch and/or one or more guide rails. The fingernail notch may be a single depression formed to allow a fingernail to slip onto the battery pack, may be a single depression and a ledge that are side-by-side, or may be formed of multiple ledges and/or depressions. There may be a single guide rail or multiple guide rails. Each guide rail preferably has a hollow interior section that is crossed by one or more ribs or segments.

FIELD OF THE INVENTION

The present invention relates to a battery pack and, more particularly,to a battery pack used in a mobile communications device.

BACKGROUND

Current wireless handheld mobile communication devices perform a varietyof functions to enable mobile professionals to stay current withinformation and communications, such as e-mail, corporate data andorganizer information while they are away from their desks. A wirelessconnection to a server allows a mobile communication device to receiveupdates to previously received information and communications. Thehandheld devices optimally are lightweight, compact, and low power tofacilitate usage by professionals on the go. It is desirous that thebattery pack powering a handheld device be made small and compact toachieve an overall lightweight device. At the same time, it is importantthat the handheld device be supplied with the correct battery pack foroptimal performance and to prevent damage through a physical and/orelectrical mismatch. Furthermore, a battery pack needs to be properlymountable for secure placement, easy removal, and reliable contactbetween the battery pack power and data terminals and the handheldmobile communication device contacts. The lid covering the battery packshould be sufficiently positioned with respect to the battery pack tosufficiently retain the battery pack terminals in contact with theterminals of the mobile communication device and, optionally, spaced toavoid shocks on the lid to be transferred to the battery pack.

Therefore, it would be desirable for a battery in a mobile handheldcommunication device to safeguard against the placement of an improperbattery and the potential resultant damage to the device; to provide amechanical guide mechanism for a cover or door to ensure properplacement of the door when secured to the device; to provide a mechanismon the battery body to facilitate removal of the battery; to provide athinner battery package to provide greater ease of use; and to have theconnector pins properly contact the battery terminals.

SUMMARY

The battery pack of the present invention offers improvements over theprior art through a synergy of structural elements. The structuralelements and their arrangement may be varied such that certainstructural elements appear in one embodiment but not another. Theimproved battery pack arises from one or more of the followingstructural elements: 1) placing a notch on the bottom side of thebattery aids in preventing placement of an improper battery and acts toretain the battery within the mounting compartment without unnecessaryside to side movement; 2) placing guide rails (or guides) on the side ofthe battery opposite to the terminals, for example, the guides may beribbed or solid and/or the guides may be molded with ribs or have theribs removed; 3) a fingernail groove or notch that aids a user to removethe battery—instead of a single groove, there may be multiple parallelgrooves in a corrugated manner—the fingernail groove may be flush withthe side surface of the battery or may be indented into the batterybody; 4) using the “hot melt” method of battery construction to minimizethe battery pack size; and 5) the molding at one end of the pins ischamfered to facilitate full contact between the connector pin and thebattery terminal.

Other aspects and features of the present invention will become apparentto those of ordinary skill in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures. It is to be understood that both the forgoinggeneral description and the following detailed description are exemplaryand explanatory only and are not restrictive of the invention asclaimed. The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate an embodiment of theinvention and together with the general description, serve to explainthe principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 illustrates a block diagram of an exemplary mobile device thatuses the battery pack;

FIG. 2 illustrates a front perspective view of a first embodiment of thebattery pack;

FIG. 3 illustrates a rear perspective view of the first embodiment ofthe battery pack;

FIG. 4 illustrates a frontal view of the terminal plate in the firstembodiment of the battery pack with a first embodiment of a guide;

FIG. 5 illustrates a frontal view of the non-terminal plate in the firstembodiment of the battery pack;

FIG. 6 illustrates a front perspective view of a second embodiment ofthe battery pack;

FIG. 7 illustrates a rear perspective view of the second embodiment ofthe battery pack;

FIG. 8 illustrates a frontal view of the terminal plate in the secondembodiment of the battery pack;

FIG. 9 illustrates a frontal view of the non-terminal plate in thesecond embodiment of the battery pack;

FIG. 10 illustrates a second embodiment of a guide for the non-terminalplate of a battery pack;

FIG. 11 illustrates a third embodiment of a guide for the non-terminalplate of a battery pack;

FIG. 12 illustrates a fourth embodiment of a guide for the non-terminalplate of a battery pack;

FIG. 13 illustrates an embodiment of an wireless handheld communicationsdevice having a receptacle for a battery pack and a mating projectionfor the battery pack;

FIG. 14 illustrates the embodiment of FIG. 13 in which a battery havingfront and back injection moulded plastic plates is inserted into thereceptacle;

FIG. 15 illustrates a perspective view of an embodiment of a lid thatfits over the battery pack when seated in the receptacle;

FIG. 16 illustrates a side view of the embodiment of the lid of FIG. 15;

FIG. 17 illustrates the lid of FIG. 15 in a mounting relation to abattery pack;

FIG. 18 illustrates another embodiment in which the lid of a mobilecommunications device has only one projection that overlaps a side of abattery pack;

FIG. 19 illustrates a second embodiment of a projection of a lid on thenon-terminal plate side of a battery pack; and

FIG. 20 illustrates a third embodiment of a projection of a lid on thenon-terminal plate side of a battery pack.

DETAILED DESCRIPTION

A battery pack, preferably using a hot melt process, has a terminal sideinjection moulded plastic plate attached to one side and a non-terminalinjection moulded plastic plate attached to the opposing side. Thebattery pack may be inserted in a common vertical mode in which theterminals are located upward with respect to a user holding a handheldmobile communication device in a normal manner. Alternatively, thebattery pack may be inserted sideways such that the terminal side plateis considerably nearer one side of the handheld mobile communicationdevice than the other side. A notch is preferably formed on the terminalside to mate with a mating projection of the battery pack receptacle ofthe handheld mobile communication device. The non-terminal plate,especially for the sideways mode, may have a structure so as to permitmating with a lid of the handheld mobile communication device. Thestructure may be implemented as one or more guides. These guides mayhave a perimeter with interconnecting ribs in accordance withlimitations imposed by the hot melt process and in accordance withrequirements for size, mating capability, resiliency, strength, and thelike.

FIG. 1 illustrates a handheld mobile communication device 10 including ahousing, an input device (a keyboard 14), and an output device (adisplay 16), which is preferably a full graphic Liquid Crystal Display(LCD). Other types of output devices may alternatively be utilized. Aprocessing device (a microprocessor 18) is shown schematically in FIG. 1as coupled between the keyboard 14 and the display 16. Themicroprocessor 18 controls the operation of the display 16, as well asthe overall operation of the mobile device 10, in response to actuationof keys on the keyboard 14 by a user.

The housing may be elongated vertically, or may take on other sizes andshapes (including clamshell housing structures). The keyboard mayinclude a mode selection key, or other hardware or software forswitching between text entry and telephony entry.

In addition to the microprocessor 18, other parts of the mobile device10 are shown schematically in FIG. 1. These include: a communicationssubsystem 100; a short-range communications subsystem 102; the keyboard14 and the display 16, along with other input/output devices including aset of auxiliary I/O devices 106, a serial port 108, a speaker 110 and amicrophone 112; as well as memory devices including a flash memory 116and a Random Access Memory (RAM) 118; and various other devicesubsystems 120. The mobile device 10 is preferably a two-way radiofrequency (RF) communication device having voice and data communicationcapabilities. In addition, the mobile device 10 preferably has thecapability to communicate with other computer systems via the Internet.

Operating system software executed by the microprocessor 18 ispreferably stored in a computer readable medium, such as the flashmemory 116, but may be stored in other types of memory devices, such asa read only memory (ROM) or similar storage element. In addition, systemsoftware, specific device applications, or parts thereof, may betemporarily loaded into a volatile store, such as the RAM 118.Communication signals received by the mobile device may also be storedto the RAM 118.

The microprocessor 18, in addition to its operating system functions,enables execution of software applications on the mobile device 10. Apredetermined set of software applications that control basic deviceoperations, such as a voice communications module 130A and a datacommunications module 130B, may be installed on the mobile device 10during manufacture. A cell mapping module 130C may also be installed onthe mobile device 10 during manufacture, to implement aspects of thepresent invention. As well, additional software modules, illustrated asan other software module 130N, which may be, for instance, a personalinformation manager (PIM) application, may be installed duringmanufacture. The PIM application is preferably capable of organizing andmanaging data items, such as e-mail messages, calendar events, voicemail messages, appointments, and task items. The PIM application is alsopreferably capable of sending and receiving data items via a wirelessnetwork 140. Preferably, the data items managed by the PIM applicationare seamlessly integrated, synchronized and updated via the wirelessnetwork 140 with the device user's corresponding data items stored orassociated with a host computer system.

Communication functions, including data and voice communications, areperformed through the communication subsystem 100, and possibly throughthe short-range communications subsystem 102. The communicationsubsystem 100 includes a receiver 150, a transmitter 152 and one or moreantennas, illustrated as a receive antenna 154 and a transmit antenna156. In addition, the communication subsystem 100 also includes aprocessing module, such as a digital signal processor (DSP) 158, andlocal oscillators (LOs) 160. The specific design and implementation ofthe communication subsystem 100 is dependent upon the communicationnetwork in which the mobile device 10 is intended to operate. Forexample, the communication subsystem 100 of the mobile device 10 may bedesigned to operate with the Mobitex™, DataTAC™ or General Packet RadioService (GPRS) mobile data communication networks and also designed tooperate with any of a variety of voice communication networks, such asAdvanced Mobile Phone Service (AMPS), Time Division Multiple Access(TDMA), Code Division Multiple Access CDMA, Personal CommunicationsService (PCS), Global System for Mobile Communications (GSM), etc. Othertypes of data and voice networks, both separate and integrated, may alsobe utilized with the mobile device 10.

Network access requirements vary depending upon the type ofcommunication system. For example, in the Mobitex™ and DataTAC™networks, mobile devices are registered on the network using a uniquePersonal Identification Number (PIN) associated with each device. InGPRS networks, however, network access is associated with a subscriberor user of a device. A GPRS device therefore requires a subscriberidentity module, commonly referred to as a Subscriber Identity Module(SIM) card, in order to operate on a GPRS network.

When required network registration or activation procedures have beencompleted, the mobile device 10 may send and receive communicationsignals over the communication network 140. Signals received from thecommunication network 140 by the receive antenna 154 are routed to thereceiver 150, which provides for signal amplification, frequency downconversion, filtering, channel selection, etc., and may also provideanalog to digital conversion. Analog-to-digital conversion of thereceived signal allows the DSP 158 to perform more complex communicationfunctions, such as demodulation and decoding. In a similar manner,signals to be transmitted to the network 140 are processed (e.g.,modulated and encoded) by the DSP 158 and are then provided to thetransmitter 152 for digital to analog conversion, frequency upconversion, filtering, amplification and transmission to thecommunication network 140 (or networks) via the transmit antenna 156.

In addition to processing communication signals, the DSP 158 providesfor control of the receiver 150 and the transmitter 152. For example,gains applied to communication signals in the receiver 150 and thetransmitter 152 may be adaptively controlled through automatic gaincontrol algorithms implemented in the DSP 158.

In a data communication mode, a received signal, such as a text messageor web page download, is processed by the communication subsystem 100and is input to the microprocessor 18. The received signal is thenfurther processed by the microprocessor 18 for an output to the display16, or alternatively to some other auxiliary I/O devices 106. A deviceuser may also compose data items, such as e-mail messages, using thekeyboard 14 and/or some other auxiliary I/O device 106, such as atouchpad, a rocker switch, a thumb-wheel, or some other type of inputdevice. The composed data items may then be transmitted over thecommunication network 140 via the communication subsystem 100.

In a voice communication mode, overall operation of the device issubstantially similar to the data communication mode, except thatreceived signals are output to a speaker 110, and signals fortransmission are generated by a microphone 112. Alternative voice oraudio I/O subsystems, such as a voice message recording subsystem, mayalso be implemented on the device 10. In addition, the display 16 mayalso be utilized in voice communication mode, for example, to displaythe identity of a calling party, the duration of a voice call, or othervoice call related information.

The short-range communications subsystem 102 enables communicationbetween the mobile device 10 and other proximate systems or devices,which need not necessarily be similar devices. For example, theshort-range communications subsystem may include an infrared device andassociated circuits and components, or a Bluetooth™ communication moduleto provide for communication with similarly-enabled systems and devices.

Powering the entire electronics of the mobile handheld communicationdevice is a power source 170. Preferably, the power source 170 includesone or more batteries. More preferably, the power source 170 is a singlebattery pack, especially a rechargeable battery pack.

FIGS. 2 to 5 illustrate a first embodiment of a battery pack for use ina mobile handheld communication device. The battery pack is a strippeddown (or bare) version of a cell with an added thin protective coating(e.g., a polymer or plastic coating or sheathing) that fully envelopsthe cell except at two ends. The terminal end is fitted through a hotmelt process with a plastic plate and the non-terminal end is fittedwith an injection moulded plate that serve to protect the cell andprovide other functions. The hot melt process for applying the plasticplate to the cell may be through a known hot melt technique using, forexample, a low temperature plastic melt. The terminal plate 204 coversand affixes a printed circuit board (not shown) that contains theterminals 208-214 that electrically connect the battery to provide powerto the handheld communication device. In forming the battery pack, thenon-terminal plate may be glued to one end of the cell, a printedcircuit board (PCB) may be soldered on the opposing end of the cell, andthen hot melt material may be injection moulded or the terminal platemay be otherwise bonded over the PCB. In one embodiment, terminal 208 isa negative power terminal, terminal 210 is a battery temperatureterminal, terminal 212 is a battery identification terminal, andterminal 214 is a positive power terminal. The terminal plate may bechamfered on one, two, three, or four sides of the opening leading tothe terminals 208-214. The angle of chamfer may vary between 30 and 60degrees with respect to the major face of the terminal plate 204; morepreferably, the angle of chamfer is approximately 45 degrees. Otherarrangements of the terminals are clearly envisioned. On each end of theplate 204 are two side notches 216 that are useable to mate with matingprojections in the receptacle of the handheld communication device suchthat the side notches 216 slide under the receptacle mating projectionsto help secure (or lock) the battery pack in the handheld communicationdevice. The terminal plate 204 may also have a bottom notch 218 thatmates with another mating projection in the receptacle of the handheldcommunication device. The bottom notch 218 may be a generallyrectangular indentation into the terminal plate 204 or may be shaped tohelp uniquely identify the battery pack type. For instance, analternative shape of the bottom notch may taper into the terminal plate204. The tapered shape may be curved and/or trapezoidal.

The dimensions of the terminal plate 204 will correspond to the size ofthe cell of the battery pack and may vary somewhat in relation to it.For example, the terminal plate 204 may be somewhat larger in extentthan the cross section of the cell with coating to better protect theend of the cell in case of slight misalignment of the terminal plate tothe end of the coated cell. Alternatively, the terminal plate 204 may bethe same size as the cross section of the coated cell or may even besmaller than the cross section of the coated cell. The non-terminalplate 220 is preferably sized similarly to the terminal plate 204 or mayvary in size relative to the terminal plate 204. The non-terminal plate220 may be a single flat shaped piece of plastic that is uniformlysmooth or it may contain features to facilitate removal and/or retentionof a lid that fits over the receptacle. In an embodiment, thenon-terminal plate 220 has a fingernail notch 230 that extendslengthwise in which a minor depression 230 is formed into thenon-terminal plate and a minor ledge 232 is formed extending outwardfrom the face of the non-terminal plate 220. There may be multipleledges and depressions that extend at varying depths into and heightsfrom the face of the non-terminal plate such that a curved corrugatedpattern is established to facilitate placement and retention of afingernail or fingertip in removing a battery pack from the receptacle.Alternatively or additionally, the non-terminal plate 220 may have oneor more guides or guide rails 222. FIG. 5 shows two guide rails 222 inwhich the upper and lower portions of the perimeter are horizontal withrespect to the non-terminal plate face length and with respect to thefloor of the handheld mobile communication device receptacle whenmounted properly. The two ends of each guide rail 222 may be curvedand/or angled to provide greater operational space for a user to accessa fingernail notch, to facilitate placement of the battery pack within areceptacle, to optimize manufacture, etc. In FIG. 5, each guide rail hasa top horizontal portion, a curved outward portion, a bottom horizontalportion, a vertical interior portion, and a slight curved portionconnecting the vertical portion to the top horizontal portion. In FIG.5, each guide rail has two supporting ribs interior to the guide rail.The rib design strengthens the guide rail and reduces the amount ofmaterial that would otherwise be used to form a completely solid guiderail of uniform thickness. Manufacturing constraints may also factor into favour a ribbed guide rail as relatively large unbroken areas of hotmelt plastic have a tendency to form undesirable depressions.

In a particular embodiment, the entire battery pack has a range ofmaximal extent from the outward face of the terminal plate 204 to theoutward face of the non-terminal plate 220 of from 40 mm to 70 mm. Inthis particular embodiment, the terminal plate may be two to fourmillimeters thick and have a face that is 4 to 8 millimeters by 25 to 45millimeters. In this particular embodiment, the face of the non-terminalplate has dimensions exactly equal to or similar to that of the terminalplate. The thickness of the non-terminal plate preferably is less thanthat of the terminal plate. For example, the non-terminal plate, may be0.5 to 1.5 mm thick and have guide rails projecting outward to add anadditional 0.4 to 1.0 mm to the thickness. The ribs and perimeterthicknesses of each guide rail is preferably 0.4 to 0.8 mm thick.

In a specific example, the battery pack with mounted plates may be 55±1mm in length end-to-end, wherein the terminal plate is 34.1±0.2 mm long,5.8±0.15 mm high, and 2.75 mm thick and the notch depths are 1.7 mm deepinto the terminal base plate 204. In this specific example, thenon-terminal plate is 34.1±0.2 mm long, 5.8±0.15 mm high, and 0.9 mmthick. In this specific example, the guide rails project 0.65 mm fromthe non-terminal plate 220, are 11.57 mm long and 3.65 mm high and haveinterior rib thicknesses and perimeter thicknesses of 0.69 mm. In thisspecific example, the guide rails are spaced from each other by adistance of 11 mm.

FIGS. 6 through 9 illustrate a second embodiment of the battery pack.The second embodiment of the battery pack is a high capacity batterypack having a markedly greater thickness than the first embodiment. Forexample, the thickness of this battery pack may range from 8 to 12 mm.In a specific example, the initial battery pack thickness is 10.8±0.15mm and the battery pack thickness after 500 cycles is approximately 11.4mm. Because of the battery pack thickness expansion from use (cycling),it is preferable to choose an adhesive melt that has expandability orflexibility. In this specific example, the terminal plate has a taperedthickness of 4 mm where the terminals are located and a minimalthickness of under 2 mm, whereas the non-terminal plate has a thicknessof 0.8 mm with guide rails extending a further 0.9 mm from the outwardface of the non-terminal plate. The fingernail notch and the guide railsare optional as in the first embodiment and are similarly dimensionrelative to the face of the non-terminal plate.

FIGS. 10 to 12 show other configurations of the guide rails of thenon-terminal plate. In FIG. 10, there is only one interior rib in anI-beam form. FIG. 11 shows a cross ribbed pattern. FIG. 12 shows a morecomplex pattern in which there are interior extensions having a verticalrectilinear segment 228 and a horizontal rectilinear segment 229 to forma T-shaped support. The T-shaped supports permit a cushioning effectwhen the projection from the lid is placed against the guide rail.Alternatively, in FIG. 12, the horizontal rectilinear segments ofopposing supports may be shared to permit a more rigid structure andoptimize processing for a particular application. In a furtheralternative embodiment, the guide rails may be generally of a U-shapedthat is laid on its side.

FIGS. 13 and 14 illustrate a sideways mateable battery pack mounted intoa receptacle of a mobile handheld communication device and thereceptacle without the battery pack so mounted. In FIG. 13, a depressionon the floor or base of the receptacle 402 permits mounting of a SIMcard 422. A mating projection 412 is present to help prevent damage thatmay be caused by an improper battery pack. The mating projection may bea simple rectangular solid of specific dimensions or may be shaped tofacilitate insertion, removal, and/or identification through physicalmating. In FIG. 14, the battery pack is placed into the receptacle suchthat the terminal plate 204 is mated with the mating projection 412 andthe non-terminal plate fits against or proximate to the opposite side ofthe receptacle.

FIGS. 15 to 20 illustrate the lid that covers the battery pack and issecured to the mobile handheld device. The lid 500 is secured to thehandheld mobile communication device 400. Securing, for example, may beaccomplished by several securing hooks on the outside edge of the lid500 (not shown). FIG. 15 shows a lid 500 with two flanges or legs 512,516 that extend in parallel to each other and the outside edges of thelid 500. Preferably, the flanges 512, 516 extend inward of the securinghooks. FIG. 16 shows that flange 516 is shorter than flange 512. Therelative heights of the two flanges 512, 516 may vary according to thedevice. In certain embodiments, flange 512 may be the only flange of thelid 500, as shown in FIG. 18. As shown in FIG. 17, flange 512 restsagainst the guide rail 222 of non-terminal plate 220 while flange 516rests against flange 204. Flange 512 and flange 516 may be sized suchthat an air gap exists between the bottom of lid 512 and the top of thebattery pack so as to provide an air pocket that is able to absorbmechanical shocks and to help channel heat away from the battery pack.The top of the terminal plate 202 or the top of the guide rail 222, 223,224 of the non-terminal plate 220 may be structured to form other than ahorizontal layer so as to better mate the lid to the housing. Forexample, as shown in FIG. 19, the top of the non-terminal plate 223 andthe bottom of flange 513 may be tapered to form a slanted junction 522that serves to guide the flange 513 to the end of the cell. As anotherexample, as shown in FIG. 20, the top of the guide rail 224 of thenon-terminal plate 220 may have a depression formed to mate with aflange 514 having a inverted U end portion such that they mate to form aconvex/concave junction. The depression may be curved as shown or may bemulti-angled such that it is formed from two or more rectilinearsegments. The guide rails may be further shaped such that the outerportion of the top of guide rail 224 is turned inward to releasablyretain the flange 514. Flange 514 may be structured to have anindentation to improve retention in such an arrangement.

The present invention is defined by the claims appended hereto, with theforegoing description being merely illustrative of a preferredembodiment of the invention. Those of ordinary skill may envisagecertain modifications to the foregoing embodiments which, although notexplicitly discussed herein, do not depart from the scope of theinvention, as defined by the appended claims.

1-26. (canceled)
 27. A battery pack comprising: a cell having a terminalend and a non-terminal end located at opposite sides of the cell,wherein the non-terminal end comprises two protruding guide rails and afingernail notch.
 28. The battery pack as claimed in claim 27, wherein apart of the terminal end is plastic.
 29. The battery pack as claimed inclaim 28, wherein the terminal end is coupled to the cell through hotmelt adhesion.
 30. The battery pack as claimed in claim 27, furthercomprising a sheathing substantially covering the cell except for theends.
 31. The battery pack as claimed in claim 30 wherein the sheathingcomprises a plastic coating.
 32. The battery pack as claimed in claim30, wherein the sheathing comprises a polymer coating.
 33. The batterypack as claimed in claim 27, wherein the terminal end comprises at leastone top corner notch.
 34. The battery pack as claimed in claim 33,wherein the at least one top corner notch is a first top corner notch ona first top corner, and the terminal end comprises a second top cornernotch on a second top corner.
 35. The battery pack as claimed in claim27, wherein: the terminal end comprises a first opening and a secondopening; the battery pack comprises a positive power terminal and anegative power terminal electrically coupled to the cell; the positivepower terminal is aligned with the first opening to permit contactbetween the positive power terminal and a first mobile communicationdevice terminal through the first opening; and the negative powerterminal is aligned with the second opening to permit contact betweenthe negative power terminal and a second mobile communication deviceterminal through the second opening.
 36. The battery pack as claimed inclaim 27, further comprising a printed circuit board electricallycoupled to the cell.
 37. The battery pack as claimed in claim 36,wherein the printed circuit board comprises: a positive power terminal;a negative power terminal; a battery temperature terminal; and a batteryidentification terminal.
 38. The battery pack as claimed in claim 27,wherein the guide rail has a flat top, a flat bottom, and a curved side.39. The battery pack as claimed in claim 27, wherein a thickness of aflattened cross section of the cell is greater than 2.75 mm and lessthan 12 mm.
 40. The battery pack as claimed in claim 27, wherein thebattery pack has a length that is greater than 40 mm and less than 70mm, a width greater than 25 mm and less than 45 mm, and a height greaterthan 4 mm and less than 8 mm.
 41. The battery pack as claimed in claim27, wherein a thickness of the non-terminal end is less than a thicknessof the terminal end.
 42. The battery pack as claimed in claim 27,wherein the terminal end comprises a bottom center notch.
 43. Thebattery pack as claimed in claim 42, wherein a shape of the bottomcenter notch is rectangular, curved, or trapezoidal.
 44. The batterypack as claimed in claim 27, wherein the terminal end is chamfered on atleast one side.
 45. The battery pack as claimed in claim 44, wherein anangle of the chamfer is greater than 30° and less than 60°.
 46. Thebattery pack as claimed in claim 27, wherein the non-terminal endcomprises at least one ledge.
 47. The battery pack as claimed in claim27, wherein the guide rail comprises an interior rib in an I-beam form.48. The battery pack as claimed in claim 27, wherein the guide railcomprises a cross ribbed pattern.
 49. The battery pack as claimed inclaim 27, wherein the guide rail comprises a vertical rectilinearsegment and a horizontal rectilinear segment.